This invention relates generally to transmitters and more particularly concerns a simplified method and apparatus for programming universal radio frequency (RF) transmitters.
Transmitters are used in a variety of applications in which wireless operation is desired. For example, most garage door openers, gate operators, and rolling shutter systems utilize transmitters to operate the movable barrier associated with the operator, (e.g., to operate the door, gate or shutter). Many of the transmitters supplied with these products are designed as single function, single frequency devices with a preset carrier frequency and use either a switch-selectable code or a preset factory code. Switch-selectable codes are set by the user setting a plurality of switches on the transmitter and the receiver units. Factory-set codes are input into the receiver by causing a controller (e.g., microcontroller or other processor such as a microprocessor, gate array or the like) within the receiver to perform a learn function. The receiver enters the learn mode, then the user activates the transmitter, which transmits a signal representing the factory programmed code stored in the transmitter.
Over the years, there have been a variety of code formats used for RF transmitters. Many of the commonly used code formats employ a fixed code format that may be set with Dual In-line Package switches (DIP switches), non-volatile memory devices, or the like. Other more secure formats include billion code format in which operators can be programmed to operate upon receipt of an authorized actuation signal which consists of a code that is selected from more than a billion possible codes. More recently, rolling code formats have become widely used in order to offer a greater degree of security.
Rolling code transmitters are preferred in such applications as remote keyless entry systems, garage door operators, etc. An example of a rolling code generating transmitter of the type described herein is disclosed in U.S. patent application Ser. No. 08/873,149 filed Jun. 11, 1997, now U.S. Pat. No. 6,154,544 issued Nov. 28, 2000, which is assigned to Applicants' assignee and is hereby incorporated herein by reference.
Fixed code RF transmitters are preferred in such applications as gate operators, which are typically operated by many more users than a garage door operator, because they are easy to program-making it easier to add/program additional transmitters to be used with the gate operator. For example, additional DIP (or fixed) coded RF transmitters can be programmed simply by matching the fixed command code, (e.g., the code identified by the various position of the DIP switches), of the added transmitter to other RF transmitters programmed for operating the gate. This eliminates the need to go through a lengthy programming sequence.
In addition to the various code formats used, several transmitter manufacturers have developed their own modulation format and have selected their own carrier frequencies for transmitting coded signals. For example, some garage door operator manufacturers transmit actuation signals consisting of packets of ten bit codes at 300 MHZ (Multi-Code), others transmit packets of eight bit or ten bit codes at 310 MHZ (Linear/Moore-O-Matic/Stanley), while still others transmit packets of nine bit, twelve bit, or twenty bit codes at 390 MHz (Genie/Chamberlain).
Unfortunately, transmitters often stop working, break, become damaged and/or get lost before their respective receivers die out. When this happens, it often becomes necessary to purchase a new transmitter. Most manufacturers who sell products using transmitters offer replacement transmitter units for sale for a period of time. However, as manufacturers improve their products by offering greater functionality, the cost of providing replacement parts for older model units increases and over time makes the manufacture of some transmitters impractical to do. In addition, the aftermarket for replacement transmitters is brisk, which leaves little incentive for a company to fill this gap and provide nothing but replacement transmitters. As a solution to these problems some companies offer universal transmitters for sale which can be used on a variety of products made by a variety of manufacturers.
In order to operate properly, universal transmitters must be capable of transmitting a plurality of different codes at a plurality of different code modulations and frequencies (or carrier frequencies). These transmitters are often sought after because consumers do not always know what type of transmitter they need, or prefer having the security of knowing that the transmitter they are buying will work with their system. Universal transmitters are also attractive to personnel who install and service movable barrier operators because they reduce the number of transmitters the installers need to stock and reduce the number of transmitters they need to learn how to program and/or operate.
In order to offer these capabilities, however, the electronic circuits used within the transmitter become more complex, larger and expensive. One drawback to requiring more complex circuitry is that the addition of components can often create RF interference among the other components and/or require redesign of the circuit layout. Similarly, the added electronics often increase the size and expense of the circuit and may require the use of a larger, more expensive microprocessor or controller. Typically, only a portion of the larger controller is used which increases waste and lowers the efficiency of the overall circuit. Another drawback to requiring more complex circuitry is that the transmitter often becomes harder for a user to program. For example, some universal transmitters require the user to perform a lengthy sequence of pressing and releasing the user inputs in order to enter the learn mode and/or program the transmitter. Therefore, designing a universal transmitter which can operate at multiple frequencies for multiple code formats, while making the programing of the transmitter less complicated is the aftermarket supplier's greatest challenge.
To date, several attempts have been made to provide universal transmitters. One example is U.S. Pat. No. 5,564,101 to Eisfeld et al. which discloses a universal transmitter for use with a garage door opener that allows for a user to program a transmitted modulation format and carrier frequency and transmit a signal corresponding to the selections. This transmitter uses two sets of mechanical DIP switches to select the transmitter code and carrier frequency. Such a configuration requires a larger controller having additional I/O ports, which will make the circuit more complex, increase the overall circuit size, raise costs, and result in making the transmitter more complicated to program.
U.S. Pat. No. 5,661,804 to Dykema et al. discloses a learning transmitter which can operate a plurality of different receivers employing rolling or encrypted code. No user input is required to learn the code and frequency, other than activating the transmitter to be copied. A single RF circuit, phase locked loop frequency synthesizer and dynamically tunable antenna are provided for learning and transmitting the desired code. Unfortunately, not all transmitters are functional when they are being replaced, so learning transmitters are not always available substitutes. In addition, transmitters which use single multi-frequency transmitter loops to generate signals at a variety of frequencies require additional time to manufacture-due to the increased time required to tune the transmitter loop appropriately-which increases the manufacturing costs and lowers the profitability of the transmitter for the manufacturer.
While all of these systems are capable of operating a plurality of receivers, each is complex, expensive, and difficult to program. Accordingly, there is a need for a simple, smaller, and less expensive transmitter capable of transmitting a plurality of different codes at a plurality of different modulations and frequencies. There is also a need for a new way of programing a universal transmitter that is less complicated and easier to perform.